Explosive Dust

Coal dust can be explosive, in the right concentration. Grain dust can become explosive. Of course natural gas and gasoline fumes can be explosive too.

Apparently smoke does not ever become explosive? Is that because it's already the byproduct of combustion?

Was thinking about this because in the Coen brothers movie everybody smoked, the rooms were full of clouds of it. In 1949 people smoked everywhere, restaurants, theaters, airplanes, cars -- and nobody ever blew up.

Yes. This type of explosion is really very fast burning. Coal can burn. Grain can burn. Ash can't.

Some smokes can burn. It depends on the fuel and the completeness of the initial combustion. Cigarette smoke is not flammable, as it is mostly water vapor and CO2.

True. If there's enough unburnt fuel in the smoke, you can have an issue. Some car backfires happen when a problem leads to unburnt fuel in the exhaust. When that catches fire in the exhaust, that makes the bang.

Yes, but that isn't smoke in the tail pipe - it's raw fuel.

Ah, you're blowin' smoke up my tailpipe.

Whether it's small droplets of liquid fuel or small grains of solid fuel doesn't make much difference, as long as you get the right size of particle and the right fuel-air ratio.